The present disclosure relates to a sensor assembly and method of making the same. More particularly, the present disclosure relates to connecting a spool assembly containing the sensor element to a harness assembly. Still more particularly, the present disclosure relates to a sensor assembly, wherein electrical interaction between the spool assembly and the harness assembly results in elimination of an over-mold interface between the harness assembly and a housing in which the spool assembly is disposed.
Virtually all such sensors are of the magnetic type, either variable reluctance or galvanomagnetic (e.g. Hall generators or magnetoresistors). Galvanomagnetic or digital sensors are becoming progressively more preferred due to their capability of greater encoding flexibility and speed independent output signals. Magnetic sensors operate on the principle of detecting magnetic flux density modulation caused by the movement of appropriately configured reluctors (or targets).
Variable reluctance (VR) sensors and digital sensors are commonly designed having an integral harness assembly. The harness assembly includes a connector assembly at one end for operable electrical connection as an input and a grommet that is over-molded to the wiring harness having leads extending therefrom at an opposite end for operable electrical connection with a sensor element of a spool or holder assembly. The spool assembly is then disposed within a sensor housing or cap.
Prior art sensor assemblies having harness leads extending from the harness assembly are typically crimped to leads extending from the spool assembly for electrical connection therewith. The sensor housing or cap open at one end is then slid over the spool assembly resulting in a subassembly that is then over-molded to form an over-molded seal cover. The over-molded seal cover is disposed over a perimeter of both the cap and grommet to seal the crimped electrical interface between the grommet and the spool assembly by sealing the open end of the cap with the over-mold grommet. After the subassembly is over-molded, brackets, o-rings, clips, and the like may be added to complete the sensor assembly.
With regard to production of an integrated assembly, the prior sensors have presented some challenges. In particular, VR and digital sensors include a large number of delicate parts that must be maintained in a connected state during packing in a housing. The crimped wire connections between components are particularly fragile. The crimped wire connections have been known to break easily during over-molding, as a result of thermal stress, thermal cycling and/or vibration during servicing and for other reasons. Over-molding a sensor having 40 gauge wire is a primary cause of stress that the sensor experiences and can also accelerate failures in less than desirable soldered and crimped terminal connections. In addition, the difference in thermal coefficients of expansion between the plastic, coil wire, harness and crimped terminal connections may cause the sensor to fail prematurely in the field
It would be desirable to have a sensor assembly that would overcome the above disadvantages without involving extra steps and expense.
A sensor package and method of manufacturing for magnetic sensing in a vehicle is disclosed. In an exemplary embodiment, a sensor package includes a holder assembly having two sensor terminals extending therefrom. The sensor terminals are in electrical communication with a sensor element configured for electromagnetic sensing. The holder assembly is configured for disposing the sensor element therewith. A harness assembly includes a connector at one end for connection with another device and a harness head at an opposite end in electrical communication with the connector. The harness head includes two harness terminals extending therefrom configured for electrical communication with the corresponding sensor terminals. The sensor package also includes a means for snap-fit assembly between the holder assembly and the harness head. The sensor package further includes a sensor housing having a cavity for receiving a sensor subassembly therein, the sensor subassembly including the holder assembly assembled with the harness head. The sensor housing has a sealable interface with the harness head. The sealable interface is configured to admit and secure the sensor element therein and provide protection from an outside environment.
In another embodiment, a method for manufacturing a sensor package is disclosed. The method includes: configuring a harness head having a pair of harness terminals extending therefrom for operable electrical communication with a sensing element and configuring a holder assembly to maintain the sensing element in a lower portion of the holder assembly and maintain a pair of sensor terminals extending from an upper portion of the holder assembly; the pair of sensor terminals are in electrical communication with the sensing element. The method further includes configuring the harness head and holder assembly with a corresponding means for snap-fit assembly to each other and connecting the pair of harness terminals with the pair of sensor terminals. A sensor housing is configured to seal the sensing element and the connected terminals from an outside environment. A resultant subassembly having the harness head assembled with the holder assembly is inserted into the sensor housing and harness head is heat-staked with the sensor housing to fix the subassembly relative to the sensor housing.
The above-discussed and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following brief description of the drawings.